Polyester-Imide Composition for Low-Dielectric PCB Films
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Solution Overview
Problem
Existing polymer compositions for printed circuit boards fail to meet the requirements of low dielectric constant (Dk < 4.0) and low dissipation factor (Df < 0.004) necessary for 5G applications, while also needing high glass transition temperature (Tg > 280°C) and thermal resistance, and must be readily film-formable by solution casting.
Innovation Solution
A polymer comprising specific proportions of dianhydrides and diamines, forming a poly(ester-imide) with recurring units linked by imide and ester groups, achieving a high Tg of at least 280°C, low Dk ≤ 3.7, and low Df ≤ 0.0036, suitable for film formation by solution casting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional polymer compositions are used for printed circuit boards, then mechanical strength and processability are maintained, but dielectric constant and dissipation factor cannot meet 5G application requirements (Dk < 4.0, Df < 0.004)
Solution Approach 1:
The patent modifies the chemical composition parameters of the polymer by incorporating specific aromatic diamines with electron-donating groups and controlling the molar ratios of dianhydride to diamine components. This changes the dielectric properties (reducing Dk and Df) while maintaining processability through solution casting by adjusting the chemical structure parameters of the polymer chains.
Solution Approach 2:
The patent creates a composite polymer system combining multiple dianhydride components (e.g., BTDA, PMDA) with specific diamine components (e.g., m-tolidine, p-tolidine) in controlled proportions. This composite structure achieves the desired dielectric performance by combining the beneficial properties of different monomers while maintaining overall material processability.
2Reliability
If polymer composition is modified to achieve low dielectric constant and low dissipation factor, then 5G frequency performance improves, but glass transition temperature may decrease below required threshold (Tg > 280°C)
Solution Approach 1:
The patent introduces localized electron-donating groups (methyl, ethyl, propyl substituents) at specific positions on the aromatic rings of the polymer structure. These local modifications reduce the overall dielectric constant and dissipation factor while the rigid aromatic backbone structure maintains the high glass transition temperature required for thermal resistance.
Solution Approach 2:
The patent carefully controls the molar ratio parameters of dianhydride to diamine components and the substitution patterns on aromatic rings. By optimizing these chemical parameters, the polymer achieves the desired dielectric properties (low Dk and Df) while maintaining Tg above 280°C through appropriate molecular structure design.
3Temperature
If high glass transition temperature and thermal resistance are achieved, then thermal stability improves, but dielectric constant and dissipation factor may not meet 5G requirements
Solution Approach 1:
The patent modifies the chemical structure parameters by incorporating electron-donating aromatic groups (m-tolidine, p-tolidine) into the polymer backbone. This structural parameter change simultaneously achieves high thermal stability (Tg > 280°C) through the rigid aromatic framework and low dielectric properties (Dk < 4.0, Df < 0.004) through the electron-donating character of the aromatic substituents.
Solution Approach 2:
The patent creates a composite polymer structure combining rigid aromatic dianhydrides (providing thermal stability) with electron-donating aromatic diamines (providing low dielectric properties). This composite approach at the molecular level achieves both high Tg and excellent dielectric performance required for 5G applications.
4Reliability
If electron-donating groups are introduced to reduce dielectric constant, then signal transmission performance improves, but polymer structure complexity increases
Solution Approach 1:
The patent introduces electron-donating groups (methyl, ethyl, propyl) at specific local positions on the aromatic rings rather than throughout the entire polymer structure. This localized modification achieves the desired dielectric properties while maintaining relative structural simplicity and regularity in the polymer backbone.
Solution Approach 2:
The patent optimizes the substitution parameters on aromatic rings (position and type of electron-donating groups) to achieve the desired dielectric performance with minimal structural complexity. By carefully selecting the substitution patterns and maintaining regular polymer structure, the patent balances dielectric properties with structural simplicity for manufacturability.
Data Source
AI summary
The invention relates to a polymer (PEI) comprising at least 90.0 mol%, preferably at least 95.0 mol%, this proportion in mol% being relative to the total number of recurring units in the polymer, of recurring units (RPEI), formed by reaction of the dianhydrides of the dianhydride component (a) and of the diamines of the diamine component (b) followed by imidization, where the dianhydride component (a) consists essentially of or consists of between 68.0 mol% and 82.0 mol% of the dianhydride (DI1) of formula and between 18.0 mol% and 32.0 mol% of dianhydride (DI2) selected in the group consisting of the dianhydride (DI2a), dianhydride (DI2b) and a combination thereof: where these proportions in mol% are given relative to the total proportion dianhydrides in the dianhydride component (a); and the diamine component (b) consists essentially of or consists of between 68.0 mol% and 100 mol% diamine (DA1) of formula where R is a substituent selected in the groups of C1-C10 alkyl groups and i an i' are integers between 0 and 4 such that i+i' is at least 2 and between 0 and 32.0 mol% of diamine (DA2) of formula where these proportions in mol% are given relative to the total proportion diamines in the diamine component (b).